(a) The Field of the Invention
This invention refers to wads and wad assemblies for shot cartridges for hunting and shooting. More particularly, this invention refers to wad assemblies formed of one piece, generally including a cup-like shot charge container; a bottom piece intended to be superimposed over the propellant charge and to provide a sliding seal in the gun barrel by acting as a piston to avoid any dispersion of the propellant energy; and additionally an intermediate part which accomplishes the primary task of the wad, which is to amortize the violent thrust applied to the inert mass of the shots as a result of the detonation of the powder.
(b) The prior art
The wads or wad assemblies (actually the word "wad" should properly refer only to the aforesaid intermediate amortizing part, which substitutes for the traditional felt wads) according to the invention are made of thermoplastic, polymeric, substantially deformable material (generally a polyethylene resin) and the actually deformable portion thereof has an essentially reticular structure which includes segments or sections susceptible of bending elastic deformation.
The correct function of the wads, and more specifically of their deformable portion, is very important, not only advantageously to reduce the physiological effect of the recoil, but also to secure the regular propulsion of the shot mass and the distribution thereof in a precisely predetermined and regularly distributed shot pattern. It is particularly important that the shot pattern be regularly reproduced at every shot, which implies that the different wads employed for charging different cartridges behave in the same manner. Their behaviour therefore must be such as not to create different elastic or permanent deformations in different wads or asymmetrical deformations in the wads, or to apply to the shot charge, at the moment of the detonation and during the shot's motion through the gun barrel, propulsive forces not exactly alined with the barrel axis.